This allows to not use the internal game state directly from client
code.

This is done to propagate the chosen variadic play cost to the
card implementation.

* Implement move artifact action
* Fix widget update memory leak
  * update the highlights not during on each frame
  * do not update the unchanged label of a button
* Allow to exit the game by pressing 'q'
* Implement some cards from the magic set
* Improve permanent formatting
* Some tweaks to UnitAI code

* implement dopping piles
* implement simple spell targeting
* add some simple spells

Panicf includes a stacktrace and causes a debugger to halt.

* Add more TODOs
* Implement permanents granting more spawn tiles

* detect tokens and do not add them to pile of cards
* only add spells not already in exile to their owners discard pile
* add the played card to onPlay callback

* implement most of the kraken cards
* unify permanent marks
* add state based actions hook for card implementations